Information recording carrier and method of reproducing the same

ABSTRACT

Plural grooves or lands formed in an information recording carrier include at least a wobbling region and data is recorded wobblingly in this wobbling region by frequency shift modulation while recorded digitally with a single or multiple waves as a channel bit.

This application is a continuation patent application of U.S.application Ser. No. 12/285,504, filed Oct. 7, 2008, which is acontinuation of U.S. patent application Ser. No. 11/434,186, filed onMay 16, 2006, which is a continuation patent application of U.S. patentapplication Ser. No. 10/245,757, filed on Sep. 18, 2002, now U.S. Pat.No. 7,088,670, the entire content of which is hereby incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an information recording carrier foruse in system for recording and/or reproducing information by opticalmeans.

2. Description of the Related Art

Conventionally, a system for reading out information by moving theinformation recording carrier relatively has been available and opticalmeans, magnetic means and electrostatic capacity means are used forreproducing information therefrom. Of them, the system for recordingand/or reproducing information by the optical means has prevailed widelyin daily life (“recording/reproducing” mentioned here means threestatuses, namely, only recording, only reproduction or recording andreproduction).

For example, as a recording/reproducing type information recordingcarrier using beam having wavelength λ=650 nm, DVD-RAM, DVD-RW (“DVD”means digital versatile disc) and the like are available.

Although the recording/reproducing type information recording carriershave been developed as actual products and marketed, the technology forburying address information into such recording/reproducing typeinformation recording carrier effectively has been still being developedand a next generation information recording carrier will needimprovement of the conventional address recording technology or a newaddress recording technology.

The first purpose for burying address information effectively is to buryaddress information at a low error rate without substantially decreasingan area provided for recording/reproducing, and the second purpose is tobury the address information by suppressing the error rate of recordingmark so that buried address information never interferes with a mainrecording/reproducing region.

As for the first object, for example, in the information-recordingcarrier employing a header type address represented by DVD-RAM (DVDrewritable), the address information is recorded by pit row (calledheader) by cutting a main recording/reproducing region. Because theheader has the same format as the reproduction dedicatedinformation-recording carrier, the error rate of the address informationis suppressed very low.

However, because recording cannot be achieved in this header region, theentire capacity of an information-recording carrier whose area islimited drops. Thus, address recording system not using the header isnecessary.

As for the second object, in the information recording carrier employingland pre-pit type address represented by for example, DVD-RW (DVDrerecordable), the recording/reproducing region is continuous and has nocut area. Although the address information is prepared as pits, thatpits (land pre-pits) are dispersed widely so that they are recordedbetween a recording track and another recording track.

Thus, although the recording capacity does not drop, the land pre-pitand the recording signal (recording mark) interfere with each otherbecause they are disposed in parallel. Consequently, the error rate ofaddress rises so that the error rate of the recording mark may rise insome cases. Thus, an address recording system using no land pre-pit isnecessary.

To solve such a request, there is a method for recording the addressinformation by forming a groove substantially parallel to theinformation recording carrier continuously such that it is wobbled.

For example, for the rewritable DVD disc (so-called DVD+RW) described inECMA/TC31/99/43, an address recording method of wobbling the groove byphase shift modulation is determined. Because according to thisrecording method, an address is recorded in the groove by phase shiftmodulation, the header is not necessary and the capacity is not lost.

FIG. 1 shows the concept of the phase shift modulation in thisrewritable DVD disc.

As the minute pattern, plural substantially parallel groove continuities150 are formed. Each of the continuities 150 is comprised of a groove151 and an inter-groove portion 152 such that both are formedsubstantially parallel to each other.

In the meantime, the groove 151 and the inter-groove portion 152 havedifferent heights (a difference in height is for example, λ/8n when therecording wavelength is λ and the refractivity of a recording lighttransmitting member is n). Then, the groove 151 is wobbled in the shapeof sine wave.

The address is recorded such that phase information is given to thisgroove 151 as shown in FIG. 2. That is, sin 0 and sin π are handled as 0and 1 when the address information is recorded. Because uponreproduction, a phase switching point 153 is loaded with the addressinformation, it can be reproduced by for example, envelop phasedetection of the push-pull signal.

If the address information is recorded by phase shift modulation likethis, the header is not necessary and the capacity is not lost. Further,reproduction is enabled by well known envelope phase detection.

When the inventor of the present invention considered this addressrecording method under various unfavorable conditions, morespecifically, recorded user data into the groove 151 in a disc of phasechange type created based on this method and tried to reproduce theaddress, it was found that the recorded user data leaked into theaddress signal thereby causing a trouble in address detection.

The frequencies for the recording data and address information neveroverlap because their information densities are different. However, inviewpoint of address reproduction, recording user data acted like noiseand it was found that detection of the address, more specificallydetection of the phase switching point 153 was often mistaken. Althoughwhen the reproduction by envelope phase detection was replaced with thereproduction by synchronous phase detection as its countermeasure, theerror rate dropped by about 1 digit, the effect was not sufficient.

Further, wobbling of the sine wave was increased so as to reduce theerror rate. In this case, although there was some extent of the effect,interference increased so that the error rate of user recording worsenedor in worst case, the tracking became unstable.

This problem is originated from a fact that this address recordingmethod depends on minute change in shape of the phase switching point153.

Further, under this address recording method, address in adjacent tracksleaked so that it was mixed into main address about once every severaltracks. As a result, not only the phase switching point 153 is difficultto detect, but also this phenomenon reduces the reliability of theinformation recording carrier remarkably.

Thus, a novel recording method by other modulation than the phase shiftmodulation and based on the groove continuity structure by makingadvantage of data recording by wobbled groove has been demanded.

Therefore, the present invention proposes a groove modulation method,which can replace the phase shift modulation so as to bury the addressinformation effectively.

More specifically, the first object is to bury address at a low errorrate without reducing the area provided for recording/reproduction, thesecond object is to bury the address by suppressing the error rate of arecording mark so that it does not interfere with the mainrecording/reproduction region. The third object is to construct so thatthe buried address does not interfere with adjacent addresses.

In the meantime, the present invention considers that gallium nitridebase compound semiconductor light emission device (for example,described in Japanese Patent No. 2778405) recently developed to raisethe recording density of the information recording carrier, that is,short-wave laser which emits light in the vicinity of λ=350 to 450 nmproduces more noise than a conventional laser.

Further, although technology for forming the information recordingcarrier in multiple layers so as to increase its recording capacity hasbeen well known, it must be considered that noise in the reproducingsystem is increased by this multiple-layers.

Further, the present invention aims at corresponding to a recentlydeveloped light transmission layer incident information recordingcarrier from viewpoints of physical structure.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an informationrecording carrier in which the address is buried effectively byreferring to such updated technological background.

To achieve the above object, there is provided an information recordingcarrier having minute pattern including plural grooves or lands formedto be substantially in parallel and adjacent each other, wherein when apitch of each groove or land is P, a wavelength of a laser beam is λ anda numerical aperture of an objective lens is NA, the minute pattern isformed under a relation of P<λ/NA, the plural grooves or lands includeat least a wobbling region and data is recorded wobblingly in thewobbling region by frequency shift modulation.

In a preferred embodiment of the present invention, the wobbling regionis comprised of a region subjected to wobbling recording by frequencyshift modulation and a region subjected to wobbling recording at asingle frequency.

In a preferred embodiment of the present invention, digital recordingusing the frequency shift modulation is carried out by frequency shiftmodulation in which with a predetermined frequency having either of1-100 waves as a channel bit, the frequency is changed over for eachchannel bit.

In a preferred embodiment of the present invention, a phase relationbetween a high frequency portion and a low frequency portion composingthe frequency shift modulation is ±(π/20.5) to ±(π/0.75).

In a preferred embodiment of the present invention, a phase of a highfrequency portion and a phase of a low frequency portion are continuousat a border between the high frequency portion and the low frequencyportion composing the frequency shift modulation.

In a preferred embodiment of the present invention, the phase relationbetween the high frequency portion and the low frequency portioncomposing the frequency shift modulation is ±(π/2.5) and a phase of thehigh frequency portion and a phase of the low frequency portion arecontinuous at a border between the high frequency portion and the lowfrequency portion.

Further, to achieve the above object, there is provided an informationrecording carrier having minute pattern including plural grooves orlands formed to be substantially in parallel and adjacent each other,comprising: a supporting body having the minute pattern; a recordinglayer formed on the minute pattern formed on the supporting body; and alight transmission layer formed on the recording layer, wherein when apitch of each groove or land is P, a wavelength of a laser beam is λ anda numerical aperture of an objective lens is NA, the minute pattern isformed under a relation of P<λ/NA, the plural grooves or lands have atleast a wobbling region and data is recorded wobblingly in the wobblingregion by frequency shift modulation.

In a preferred embodiment of the present invention, the wobbling regionis comprised of a region subjected to wobbling recording by frequencyshift modulation and a region subjected to wobbling recording at asingle frequency.

In a preferred embodiment of the present invention, digital recordingusing the frequency shift modulation is carried out by frequency shiftmodulation in which with a predetermined frequency having either of1-100 waves as a channel bit, the frequency is changed over for eachchannel bit.

In a preferred embodiment of the present invention, a phase relationbetween a high frequency portion and a low frequency portion composingthe frequency shift modulation is ±(π/20.5) to ±(π/0.75).

In a preferred embodiment of the present invention, a phase of a highfrequency portion and a phase of a low frequency portion are continuousat a border between the high frequency portion and the low frequencyportion composing the frequency shift modulation.

In a preferred embodiment of the present invention, the phase relationbetween the high frequency portion and the low frequency portioncomposing the frequency shift modulation is ±(π/2.5) and a phase of thehigh frequency portion and a phase of the low frequency portion arecontinuous at a border between the high frequency portion and the lowfrequency portion.

The nature, principle and utility of the invention will become moreapparent from the following detailed description when read inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a conceptual diagram of phase-shift modulation in a rewritableDVD disc;

FIG. 2 is a conceptual diagram of the recording status of addressinformation in the rewritable DVD disc;

FIG. 3 is a diagram showing an example of the information recordingcarrier of the present invention;

FIG. 4 is a diagram showing other example of the information recordingcarrier of the present invention;

FIG. 5 is a diagram showing still other example of the informationrecording carrier of the present invention;

FIG. 6 is a diagram showing plane fine structure in the informationrecording carrier of the present invention;

FIG. 7 is a diagram showing the structure of a groove formed in theinformation recording carrier of the present invention;

FIG. 8 is a diagram showing other structure of a groove formed in theinformation recording carrier of the present invention;

FIG. 9 is a diagram showing still other structure of a groove formed inthe information recording carrier of the present invention;

FIG. 10 is a diagram showing a change in data between before base bandmodulation and after base band modulation;

FIG. 11 is a diagram showing a specific example of a change in databetween before base band modulation and after base band modulation;

FIG. 12 is a diagram showing other structure of the groove formed in theinformation recording carrier of the present invention;

FIG. 13 is a sectional view of a thin light transmitting layerinformation recording carrier;

FIG. 14 is a plan view showing the information recording carrier of thepresent invention and its reproduction method;

FIG. 15 is a sectional view showing the thin light transmitting layerinformation recording carrier and its reproduction method;

FIG. 16 is a plan view showing the information recording carrier of thepresent invention and its reproduction method;

FIG. 17 is a sectional view of the thin light transmitting layerinformation recording carrier described in FIG. 13 reconstructed to havetwo layers;

FIG. 18 is a diagram showing a first example of address informationdispersion recording;

FIG. 19 is a diagram showing a second example of address informationdispersion recording;

FIG. 20 is a diagram showing a third example of address informationdispersion recording; and

FIG. 21 is a diagram showing a fourth example of address informationdispersion recording.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the preferred embodiments of the present invention will bedescribed with reference to FIGS. 3 to 21.

First, a preferred embodiment of the present invention will be describedwith reference to FIGS. 3, 4.

An information recording carrier 1 of this embodiment of the presentinvention executes at least one of recording and reproduction mainly bymeans of optical means.

This information recording carrier 1 is, for example, phase changerecording type information recording carrier, pigment type informationrecording carrier, magneto-optical type information recording carrier,light-assist magnetic type information recording carrier.

As shown in FIG. 3, uneven fine patterns are formed in the surface(laser beam irradiating face) of the information recording carrier 1 orinside thereof as a recording/reproducing region and its plane structureis composed of parallel groove continuity 100 formed such that pluralgrooves substantially parallel adjoin each other.

Although an example of FIG. 3 indicates only part of the parallel groovecontinuity 100 in circular shape, this circular shape may be continuousaround 360° coaxially or spirally.

Although FIG. 3 represents the information recording carrier 1 as acircle, the present invention is not restricted to such a shape.

Further, the information recording carrier 1 may be formed in the formof a card shown in FIG. 4 and particularly, the parallel groovecontinuity 100 may be formed in parallel to a side of this card.

Further, the information recording carrier 1 may be formed in the formof a card shown in FIG. 5 and the parallel groove continuity 100 may beformed circularly like FIG. 3.

Additionally, although not shown, the information recording carrier 1may be formed in the form of a tape or may be bored.

In the meantime, data to be recorded under the present invention isdigital data, which is recorded at least in part of the parallel groovecontinuity 100 in the form of the shape of a groove. Therefore, this ispermanent data which cannot be rewritten.

The type of data to be recorded is not particularly specified, butaddress information, copy protection information, encrypted information,encryption key and the like can be recorded.

The address information mentioned here refers to data selected fromabsolute address allocated to the entire information recording carrier1, relative address allocated to a partial region, track number, sectornumber, frame number, field number, time information, error correctioncode and the like, for example, data obtained by converting decimal orhexadecimal data to binary data (including examples of BCD code or graycode).

To facilitate understanding, following description will handle digitaldata to be recorded as address information.

FIG. 6 shows a plane fine structure obtained by enlarging the parallelgroove continuity 100 described in FIGS. 3 to 5.

Referring to FIG. 6, a parallel groove continuity 100 comprises a track201 having at least a wobbling region and a track 203 having at leastliner groove region, and these tracks are constructed substantially inparallel in macro viewpoint while they are formed alternately.

An interval between the track 201 having the wobbling groove region andthe track 203 having the linear groove region is called inter-grooveportion 202. The track 201 having the wobbling groove region and thetrack 203 having the linear groove region have the same height, which isdifferent from the height of the inter-groove portion 202. In theinformation recording carrier of the present invention, P<λ/NA isestablished when the pitch between the track 201 having the wobblinggroove region and the track 203 having the linear groove region is P,the wavelength of reproduction light for reproducing the informationrecording carrier 1 of the present invention is λ, and the numericalaperture of an objective lens is NA.

For example, when λ=650 nm and NA=0.6 like DVD, P<1083 nm isestablished.

If for example, gallium nitride base compound semiconductor lightemission device and a high NA pickup are used, P<476 nm is establishedwhen λ=405 nm and NA=0.85 are set up.

Although the track 201 having the wobbling groove region and the track203 having the linear groove region are drawn narrower than theinter-groove portion 202 in the same Figure, the groove width of each isnot limited. Further, the width of the track 201 having the wobblinggroove region and the width of the track 203 having the linear grooveregion may be the same or different from each other.

The wobbling basic wave is not restricted to sine wave, but may betriangular wave or rectangular wave. Particularly if the sine wave isselected, no high frequency component is contained, so that excellentquality recording whose band is restricted is achieved. The track 201having the wobbling groove region and the track 203 having the lineargroove region may be both linear, coaxial or spiral. Particularly, incase of the circle or circular parallel groove continuity 100 shown inFIG. 3 or 5, the track 201 having the wobbling groove region records atconstant angular velocity (CAV) or at constant linear velocity (CLV) orzone constant angular velocity (ZCAV) or zone constant linear velocity(ZCLV) in which a different zone is formed depending on the radius sothat control of each zone is different.

The track 203 having the linear groove region may be continuous lineover 360°.

What is important here is that the wobbling groove region and the lineargroove region are disposed alternately adjacent each other andparticularly in case of a disc-like information recording medium, theseregions are disposed alternately adjacent each other in the radialdirection.

The track 201 having the wobbling groove region records data in the formof a shape gained by frequency-shift modulation and more specifically,the same track is composed of plural portions gained by wobbling thegroove at each specific frequency.

More specifically, binary data is recorded in a shape by frequency-shiftmodulation using high frequency portion and low frequency portion. If nvalue data is of multiple value, that data is recorded in a shape byfrequency shift modulation using frequency portions of n kinds. Anexample in which the data is binary will be described with reference toFIG. 7.

FIG. 7 shows an example in which data 1, 0, 1, 1, 0 are recorded in ashape, comprising high frequency portions 301 and low frequency portions300.

The high frequency portion 301 and the low frequency portion 300correspond to data bits 1 and 0 respectively. The frequency is changedfor each channel bit so as to carry out digital recording.

Here, the number of waves constituting each frequency is not limited butthe frequency is composed of one or more waves. However, if it isconsidered to detect the frequency in a reproducing apparatus accuratelyand to hamper excessive redundancy in order to acquire some extent ofdata transmission velocity, preferably the frequency portioncorresponding to each data bit is constituted in the range of 1 to 100waves, more preferably 1 to 30 waves.

The high frequency portion 301 and the low frequency portion 300 maycoincide with each other in terms of amplitude. However, there is norestriction in amplitude ratio and considering the frequencycharacteristic of the reproducing apparatus, the amplitude of the highfrequency portion 301 may be formed larger than that of the lowfrequency portion 300.

In any case, there need to be the relation of Δ<P between the amplitudeΔ and the pitch P.

In such a way, the track 201 having the wobbling groove region and thetrack 203 having the linear groove region are so constructed not tocontact each other at all, and therefore, addresses subjected tofrequency shift modulation in different tracks 201 are prevented frommixing together upon reproduction.

In the meantime, the amplitude Δ refers to the amount of deflection fromthe center line of frequency shift modulation up to the maximum point orminimum point of the wave.

It is permissible to use push-pull method for reading of recorded datalike the case of phase-shift modulation.

The information recording carrier 1 of the present invention neverrestricts the physical length and amplitude of a channel bit constitutedof the high frequency portion 301 and the low frequency portion 300.

For example, in FIG. 7, the physical length of the low frequency portion300 is set longer than that of the high frequency portion 301.

Like the track 211 having the wobbling groove region shown in FIG. 8, itis permissible that the amplitudes of the high frequency portion 303 andthe low frequency portion 302 are equal while the length of the highfrequency portion 301 is equal to that of the low frequency portion 302.

Consequently, 0, 1 determination can be carried out with an ampleamplitude threshold upon reproduction and series data can be read undera single time threshold, thereby simplifying a reproduction circuit.

Further, even if there is a jitter (deflection in time axis direction)in reproduced data, there is an advantage that its influence can beminimized. If a code to be recorded is ideally symmetrical, the totallengths of the high frequency portion 301 and the low frequency portion302 are equal, so that there is no direct current component in thereproduced signal.

As a result, there is generated no load on data decoding or servo, whichis advantageous.

In FIGS. 7, 8, the high frequency portion 301 and the low frequencyportion 302 are so connected as to rise at a switching point of thechannel bit. However, because a phase jump occurs with a probability of50% at this time, high frequency component is generated therebyworsening power efficiency per frequency.

FIG. 9 shows an example in which the high frequency portion 301 and thelow frequency portion 302 are allocated to maintain the phase continuityat the switching point of the channel bit in the wobbling groove region221 in order to improve such a problem.

That is, the start phase of the low frequency portion 304 is selected sothat the end of the high frequency portion 305 and the start of the lowfrequency portion 304 are in the same phase direction. An inverse caseis the same, accordingly the start phase of the high frequency portion305 is selected so that the end of the low frequency portion 304 and thestart of the high frequency portion 305 are in the same phase direction.Such a selection maintains continuity of the phase, improves powerefficiency and makes reproduction envelope constant, thereby improvingdata error rate of the information recording carrier 1.

Although selection of each frequency of the high frequency portion 301and the low frequency portion 302 is arbitrary, the frequency of thehigh frequency portion 301 is required not to be so much higher thanthat of the low frequency portion 302 in order to avoid an interferencewith the frequency band for user to record data in the informationrecording carrier 1.

On the other hand, it is desirable to possess some extent of adifference in frequency between the high frequency portion 301 and thelow frequency portion 302 and thus maintain an excellent separationperformance in order to ensure an excellent reproduction error rate foraddress data.

In this viewpoint, the frequency ratio (high frequency/low frequency)between the high frequency portion 301 and the low frequency portion 302is desired to be in the range of 1.05 to 5.0, particularly in the rangeof 1.09 to 1.67.

In other words, when the reference phase is set to 2π, the phaserelation of the two frequencies is preferred to be in the range of2π±(π/20.5) to ±(π/0.75) , particularly in the range of 2π±(π/12) to±(π/2) (that is, 360°±15° to ±90°).

Particularly if the frequency ratio (high frequency/low frequency) is1.5 as shown in a diagram of FIG. 9, the two frequencies are in therelation that they are obtained by shifting the phase of a single waveby −π/2.5 (high frequency) and +π/2.5 (low frequency) (that is,2π±(π/2.5) when the reference phase is 2 π). In other words, the twofrequencies are in the relation that they are shifted into 360±72°

These two frequencies can be expressed with an integer time (three timesor twice) a single frequency (0.5 here). Therefore, there is such anadvantage that the demodulating circuit can be simplified. Further, acircuit having the 0.5 window facilitates generation of clocks. Further,demodulation can be executed by means of a synchronous detectioncircuit.

As described above, the information recording carrier 1 of the presentinvention comprises a track 201 (201, 211, 221) having at least thewobbling groove region, an inter-groove portion 202 and a track 203having at least the linear groove region. These elements are formedsubstantially parallel to each other and alternately so as to constructa parallel groove continuity 100.

When the pitch between the center of the track 201 having the wobblinggroove region and the center of the track 203 having the linear grooveregion is P, the wavelength of reproduction laser beam for playing backthe information recording carrier 1 of the present invention is λ andthe numerical aperture of an objective lens is NA, there is a relationof P<λ/NA.

The groove 201 (201, 211, 221) having the wobbling region wobbles due tofrequency shift modulation and its plane structure is constituted of thehigh frequency portion 301 (301, 303, 305) and the low frequency portion300 (300, 302, 304).

Digital data is recorded in the information recording carrier 1 of thepresent invention by frequency shift modulation. Then, because 0, 1 arerecorded corresponding to a change of wobbling frequency, 0, 1determination performance is excellent. Particularly, because no finephase information is contained unlike phase shift modulation applied tothe writable DVD, a low error rate can be obtained even under arelatively small C/N. Further, even if noise overlaps when a recordingmark is recorded in the groove track (201, 203) or the inter-grooveportion 202, data recorded wobblingly in the groove track is neverdisturbed.

As for mutual interference (cross-talk) of data in adjoining grooves,because the linear groove 203 is inserted between the grooves 201 (201,211, 221) having the wobbling region, no cross-talk of address inadjacent tracks is generated.

Accordingly the data error by cross-talk is hardly generated, theaddress error rate can be maintained low even to a pattern in which adistance between adjacent tracks is changed momentarily like CLV.

The structure and effect of the information recording carrier 1 of thepresent invention have been described. The present invention is notrestricted to the information recording carrier 1 shown in FIGS. 3 to 9and may be modified and applied in various ways within the gist thereof.

For example, although sine wave is used as basic wave in description ofthe frequency shift modulation with reference to FIGS. 5 to 7, it ispermissible to use cosine wave as the basic wave.

According to the present invention, the track 201 having at least thewobbling groove region, the inter-groove portion 202, and the track 203having at least the linear groove region are formed alternately.Although the wobbling groove region provides the information recordingcarrier 1 constituted of at least frequency shift modulation, this maybe applied to the disc-like information recording carrier in variousways.

For example, as described above, the information recording carrier maycontain a plurality of enclosed tracks over 360°, the tracks beingformed coaxially.

In the information recording carrier, these tracks may be constructedspirally without overlapping or connecting the track 201, theinter-groove portion 202 and the track 203.

If the entire information recording carrier is viewed, it is comprisedof three spirals for the track 201, the inter-groove portion 202 and thetrack 203.

As a modification of this pattern, the wobbling groove region and thelinear groove region may be inverted at every predetermined angle.

Although, in the above description, a method of recording data directlyis used as the recording method, the present invention is not restrictedto this direct recording.

That is, if long address data string is recorded, the direct recordingmay generate continuation of 0 or 1, so that direct current componentmay be generated in data. To avoid this phenomenon, it is permissible toadopt a method of recording base-band modulated data. Namely, 0 and 1are converted to a different code preliminarily and continuation of 0and 1 is made below a predetermined value. As such a method, it ispermissible to use Manchester code, PE modulation, MFM modulation, M2modulation, NRZI modulation, NRZ modulation, RZ modulation, differentialmodulation or the like independently or in combination.

As a base band modulation method particularly suitable for theinformation recording carrier 1 of the present invention, Manchestercode (bi-phase modulation, 2-phase modulation) is available. Accordingto this method, as shown in FIG. 10, 2 bits are allocated to 1 bit ofdata intended to be recorded. That is, 00 or 11 is allocated to data 0intended to be recorded and 01 or 10 is allocated to data 1. Then, uponconnecting of data, it is always necessary to begin with the inversioncode of a code.

As described in FIG. 11, address data of 100001 turns to code string of010011001101. Original address data is asymmetrical data which includescontinuous four 0s and in which the appearance probability of 0 is twice1.

If this is modulated, it is converted to symmetrical data in whichcontinuous 0s or 1s are two max. and the appearance probabilities of 0and 1 are equal. The base band modulation in which continuity of thesame bits is restricted to a predetermined value or less has an effectof improving reading stability and therefore, this is a pre-processingsuitable when long address data is handled.

Additionally, there is a method in which the address data is dissolvedhighly accurately and recorded dispersedly. For example, as a firstexample of address dispersed recording, by combining with dummy data“101”, a combination of “101X” (X is 0 or 1) is recorded and this datastring is disposed at every predetermined interval.

That is, as shown in FIG. 18, “101” is disposed at a predeterminedinterval (every 11 bits here) as data trigger Tr and subsequently, X isdisposed. That is, if with “101” as data trigger Tr, only X just afterthe data trigger Tr is extracted, data can be restored.

In this example if “1” is considered to be data, data can be restored inthe order of data presence, none, presence. Thus, “101” can bereproduced as address information. This method is valid for a formatwhich permits data to be handled to be read with a time.

In the meantime, 1-bit data extracted at every predetermined interval isdefined as word and it is assumed that address information isconstructed by gathering words.

In other words, data to be recorded by frequency-shift modulation isaddress information, which is composed of data triggers provided atevery predetermined interval and data allocated between these datatriggers. In this information recording carrier, address information isrecorded depending on presence or absence of this data.

As a modification of this method, as shown in FIG. 19, it is permissibleto form the address information such that the data trigger Tr and dataare set apart at the interval of specified bits (second example ofaddress dispersed recording).

Here, data trigger Tr is “11”, so that the data trigger is disposed atevery 11 bits. Then, data is recorded at every predetermined intervaldepending on presence or absence of “101” . That is, by fetching datafrom the fourth bit to the sixth bit subsequent to the data trigger Tr,1-bit data can be restored.

Because this example enables data to be restored in the order of datapresence, none and data presence, “101” can be reproduced as the addressinformation. Because the data trigger Tr is apart from data, thisrecording method is capable of reducing reading errors.

As a third example of highly dispersed recording, the first specifieddata pattern (for example, “11”) is disposed (recorded) at everyspecified interval. The second specified data pattern (for example“101”) is disposed between the first specified data patterns. Theposition for disposing the second specified data pattern is locatedspecified bits (distance or time) ahead of the first specified datapattern and particularly, two selectable positions are allocated.

That is, as shown in an example of FIG. 20 (third example of addressdispersed recording), as the first specified data pattern, the datatrigger Tr “11” is disposed at every predetermined interval (every 11bits here) and the second specified data pattern “101” is disposedtherebetween. As the position for disposing the second specified datapattern, two ways are prepared, that is, from the third bit to the fifthbit or from the fifth bit to the seventh bit. After determining whichposition data is disposed at, decoding is carried out.

In this example, data is disposed in the order of third bit start, fifthbit start and third bit start, therefore “101” can be reproduced as theaddress information. Because this recording method allows whether or notdata “101” can be read to be added as a criterion on reliabilitydetermination, this method is effective particularly when it is desiredto provide the address information with high reliability.

In other words, data to be recorded by frequency shift modulation isaddress information and composed of data trigger provided at everypredetermined interval and data allocated at a specified positionbetween the data triggers. In this information recording carrier, theaddress information is recorded depending on a mutual distance betweenthis data trigger and data.

As the third example of the highly dispersed recording, the method ofdispersed recording using a difference in position between the firstspecified data pattern and the second specified data pattern has beendescribed. If a pattern having an extremely high reading accuracy can beprepared as the specified data pattern, the first specified data patternand the second specified pattern may be the same. That is, it ispermissible to extract a specific pattern shorter than a predeterminedtime interval in which the specified data pattern is recorded andmeasure its distance interval (time interval) so as to decode the data.

More specifically for example as shown in the fourth example of addressdispersed recording of FIG. 21, the data trigger “11” is disposed atevery predetermined interval (every 11 bits here) as the first specifieddata pattern, and the second specified data common to the Tr is disposedtherebetween. As the position for disposing the second specified datapattern, two ways are prepared, that is, from the third bit to the fifthbit or from the fifth bit to the seventh bit and data decoding iscarried out by determining which position data is disposed at. In thisexample, data is disposed in the order of third bit start, fifth bitstart and third bit start, therefore “101” can be reproduced as theaddress information.

Since this recording method only has to prepare a specified datapattern, the reproducing circuit can be simplified.

Various kinds of highly dispersed recordings have been already describedabove. That is, according to these recording methods (any recordingmethod), the address information is recorded as data divided to bits.

More specifically, first, dummy data of about several bits is preparedas data trigger Tr. Subsequently, a data string (for example, continuityof 0s) composed of continuity of single data is prepared and the datatriggers Tr are disposed in the single data string at everypredetermined interval. The address information which is divided torespective bits is recorded so as to convert part of the single datastring according to a predetermined rule. Then, bits located at aposition specified distance ahead of the data trigger are convertedaccording to a predetermined rule and recorded.

On the other hand, upon reproduction, the data triggers Tr disposed atevery predetermined interval are detected from a data string subjectedto frequency shift modulation. Then, 1-bit data (corresponding to “word”in FIGS. 18 to 21) is extracted from data excluding the data triggers Trby verifying with a predetermined rule. The extracted 1-bit data areaccumulated so as to restore address information.

Because data recorded wobblingly is capable of handling a relativelylarge number of data even if the dispersed recording method is employed,it is capable of handling not only the address data but also auxiliaryinformation.

At least a specified data can be selected from for example, type ofinformation recording carrier, size of information recording carrier,estimated recording capacity of information recording carrier, estimatedrecording line density of information recording carrier, estimatedrecording line velocity of information recording carrier, track pitch ofinformation recording carrier, recording strategy information,reproduction power information, manufacturer information, productionnumber, lot number, control number, copyright related information, keyfor creating cipher, key for decipher, encrypted data, recordingpermission code, recording reject code, reproduction permission code,reproduction reject code and the like. These data may accompany errorcorrection code.

Since the address data is smaller than main information, the track 231having wobbling groove region may be divided to two regionsmacroscopically as shown in FIG. 12.

That is, the two regions are frequency shift modulation region 400 inwhich the address data is recorded and single modulation region 401 forextracting clocks.

Hereinafter, the frequency shift modulation region 400 is called addressregion 400 and the single modulation region 401 is called clock regionfor convenience for explanation. As described up to here, the former iscomposed of high frequency portion and low frequency portion. The latteris composed of only specified frequency portion.

Although the basic wave shapes and amplitude amounts in these tworegions may be different, they are preferred to be equal ifsimplification and stabilization of the recording circuit andreproducing circuit are considered. Although as regards the frequency,the high frequency portion, the low frequency and the clock region 401may be different from each other in terms of the frequency, if any ofthe high frequency portion and the low frequency portion is equal to theclock region 401 in terms of the single frequency, the physical lengthfor use in extracting the clock can be expanded to some extent.Consequently, stabilized extraction of the clock is facilitated, whichis advantageous.

In border between these two regions, it is permissible to record thestart bit signal, stop bit signal or synchronous signal which clarifiesthis division. For example, as an example of such a signal, a singlespace (having the same height as the groove portion 232) formed bycutting the track 231, a repetition pattern of pit and space and thelike are suitable.

In FIG. 12, the shape of the basic wave in the clock region 401 is sinewave. The sine wave is preferable because a stabilized clock extractionis enabled for reproduction of clock region and no leakage of highfrequency component occurs in user data recording. In the meantime, thebasic wave shape in the clock region 401 may be also cosine wave.

Further, a single frequency for clock may be overlaid on the frequencyshift modulation region 400. That is, it is permissible to overlay afrequency different from any of the high frequency side and lowfrequency side composing the frequency shift modulation address thereon.Further, it is also permissible to overlay any frequency of the highfrequency side or the low frequency side on the frequency shiftmodulation address.

Likewise, it is also permissible to overlay a frequency an integer timesor one an integer the frequency of the high frequency side or lowfrequency side.

Because even if clock frequency is overlaid on the frequency shiftmodulation address, frequency separation is enabled with a well knownband path filter, the address and clock can be separated and reproducedindividually. Therefore, even if the frequency shift modulation region400 is formed over a long distance, stabilized reproduction is enabledbecause the clock can be extracted continuously.

Next, as application of the information recording carrier 1 of thepresent invention, adoption thereof to recently developed lighttransmission layer incident type information recording carrier will bedescribed.

The light transmission layer incident type information recording carrierhas a very thin light transmission layer of about 0.1 mm thick relativeto its entire length of 1.2 mm different from a conventional informationrecording carrier and carried out recording or reproduction whenrecording laser beam or reproduction laser beam is irradiated thereon.Such a structure is capable of corresponding to a high numericalaperture NA and increase the recording density.

FIG. 13 shows schematically the sectional structure of the lighttransmission layer incident type information recording carrier 1 and thereproduction system thereof.

Referring to the same Figure, the light transmission layer incident typeinformation recording carrier 1 comprises at least a supporting body 13,a recording layer 12 and a light transmission layer 11. Theaforementioned minute pattern constituted of groove G and land L isformed on a side of the supporting body 13 in contact with the recordinglayer 12. Then, laser beam 91 for recording or reproduction is projectedfrom the side of the light transmission layer 11 through an objectivelens 90. Light passing the light transmission layer 11 is irradiated onthe recording layer 12 so as to execute reproduction orrecording/reproduction. Although light is projected from the side of thesupporting body 13 in a conventional information recording carrier, thelight transmission layer incident type information recording carrier 1employs opposite light incident direction. As for the designation of thegroove G and land L, according to definition by Japanese IndustrialStandard (JIS), the groove L means a groove near the incident face whilethe land L means a groove far from the incident face (for example,JIS-X6271-1991).

FIG. 13 shows the positions of the groove G and land L based on thisdefinition and in this example, the groove G is irradiated with light.

In case where the aforementioned address recording was adopted to theinformation recording carrier 1 having such a structure, which of thetrack 201 having the wobbling groove region, the track 203 having thelinear groove region and the inter-groove portion 202 should be disposedin the groove G and land L was considered.

This problem is not only related to address data, but also deeplyrelated to which of the groove G and the land L data should be recordedin if user records it in or reproduces from the recording layer 12.

As a result of consideration from such a viewpoint, it was found thatgeneration of reproduction jitter and error rate could be suppressed ifuser's recording to the recording layer 12 was carried out selectivelyin only the groove G and recording repetition performance was excellent.This reason is that heat due to irradiation of the laser beam 91 is morelikely to be accumulated in the groove G than the land L because thegroove G is located more forward of (nearer) the laser beam 91 (side ofthe objective lens 90) than the land L.

As a result, not only the recording sensitivity in the groove G isintensified but also the shape of a recording mark formed there becomesuniform and therefore it is found that the groove G is capable ofachieving ideal recording.

On the other hand, if the same mark is recorded in the land L, heat byirradiation of the laser beam 91 is more likely to be radiated than thegroove G, so that the shape of the recording mark formed there becomesuneven. Thus, it is found that the land L is not capable of achievingideal recording.

If recording/reproduction is restricted to the groove G, it is foundthat the track 201 having the wobbling groove region (and track 203having the linear groove region) should be disposed on the side of theland L while the inter-groove portion 202 should be disposed on the sideof the groove G.

Namely, if this structure is opposite, the laser beam 91 is irradiatedto the center of the track 201 having the wobbling groove region, sothat address is reproduced with an output about twice as compared to acase where it is disposed on the side of the land L. However, laser beamis irradiated to the center of the track 203 having the linear grooveregion in next track, so that no address is reproduced.

Therefore, only an address is reproduced every two turns and thus, thisis not useful as the address of the information recording carrier 1.

In the meantime, a difference in height between the groove G and theland L (in other words , height of minute pattern) is preferred to beλ/8n to λ/20n if considering that push-pull reproduction is carried out.Meanwhile, n means refractivity at λ of the light transmission layer 11.Particularly, because the refractivity of the recording layer 12 dropsdue to existence of the minute pattern 20, the land L is preferred to beshallower and its depth is preferred to be less than λ/10n in order toprevent deterioration of jitter of the reproduction signal.

Further, because the output of the push-pull signal increases with thedepth of the land L upon tracking, the limit value of tracking ispreferred to be more than λ/18n. That is, λ/10n to λ/18n is preferable.

Assuming that an interval between the track 201 having the wobblinggroove region and the track 203 having the linear groove region is pitchP (the interval between the inter-groove portions 202 is pitch P also),the P satisfies the relation of P<S with respect to reproduction spotdiameter S. Here, the reproduction spot diameter is calculated withS=λ/NA where the wavelength of laser beam used for reproduction is λ andthe numerical aperture of an objective lens is NA. In other words, thepitch P satisfies the relation of, P<λ/NA.

For example because if the aforementioned bluish purple laser is used, λis in the range of 350 to 450 nm and if high NA lens is used, NA is 0.75to 0.9, the pitch P is set to 250 to 600 nm.

Further, if a case of recording digital pictures by high definitiontelevision (HDTV) for about two hours is considered, the pitch P ispreferred to be 250 to 450 nm.

Particularly, if NA is 0.85 to 0.9, the pitch is preferred to be 250 to400 nm.

Particularly, if NA is 0.85 to 0.9 and A is 350 to 410 nm, λ ispreferred to be 250 to 360 nm.

The signal system used for recording into the recording layer 12 or foruser recording may use for example, a modulation signal which is called(d, k) code. The (d, k) modulation signal can be used for not only fixedlength code but also variable length code.

For example, as an example of (d, k) modulation for the fixed lengthcode, EFM, EFM plus (8-16 modulation) with d=2, k=10; modulation signal(D8-15 modulation) described in Japanese Patent Application Laid-OpenNo. 2000-286709; (D1, 7) modulation (described in Japanese PatentApplication No. 2001-080205) with d=1, k=7; modulation signal (D4, 6modulation) described in Japanese Patent Application Laid-Open No.2000-332613 with d=1, k=9; (3, 17) modulation with d=3, k=17 and thelike are available.

Further, as an example of (d, k) modulation for the variable lengthcode, preferably, modulation signal (1, 7PP modulation) described inJapanese Patent Application Laid-Open No. HEI11-346154 (1999) with d=1,k=7; (4, 21) modulation with d=4, k=21 and the like are used.

Therefore, the sectional structure of the information recording carrier1 and the reproduction method of the present invention are shown inFIGS. 15, 14, 16.

FIG. 15 shows the sectional structure of the information recordingcarrier 1 of the present invention, which comprises the supporting body13, the recording layer 12 and the light transmission layer 11.

Here, a disc-like information recording carrier is indicated with asectional view taken in the radial direction. The minute pattern (FIG.6) is formed on a side in contact with the recording layer 12 of thesupporting body 13. Particularly, the track 201 having the wobblinggroove region and the track 203 having the linear groove region aredisposed on the side of the land L, while the inter-groove portion 202is disposed on the side of the groove G.

Laser beam 91 for recording or reproduction is projected from the sideof the light transmission layer 11 through the objective lens 90. Lightpassing the light transmission layer 11 is irradiated on the recordinglayer 12 so as to execute reproduction or recording/reproduction.

FIG. 14 is a plan view of a minute pattern (parallel groove continuity)100 for explaining the reproduction method. Therefore, the track 201having the wobbling groove region and the track 203 having the lineargroove region are disposed alternately and the inter-groove portion 202is disposed therebetween.

FIG. 15 shows a sectional view taken along the line CR of FIG. 14. Thetrack 201 having the wobbling groove region, the track 203 having thelinear groove region and the inter-groove region 202 are disposedsubstantially in parallel to each other, so that they are extendedvertically in the radial direction while in parallel in the tangentialdirection.

FIG. 14 shows the reproduction laser beam 91 also and spot light isconcentrated on the inter-groove portion 202 (side of groove G) so as toexecute reproduction or recording/reproduction. The reproduction laserbeam 91 is projected to both walls of the track 201 having the wobblinggroove region and the track 203 having the linear groove region.

Therefore, even if recording/reproduction is carried out in theinter-groove portion 202, the frequency shift modulation signal can bereproduced by push-pull method.

That is, by appropriately selecting a difference in output of a4-division photo-detector incorporated in a reproduction pickup (notshown), the push-pull signal can be generated.

In FIG. 14, the laser beam 91 is projected to the photo detector whichis divided to four sections, A, B, C, D. For example, by generating adifference in output in the radial direction, that is, (A+B)−(C+D), thepush-pull signal can be obtained. As a result, frequency-shift modulateddata can be reproduced favorably.

This push-pull signal becomes a means for being notified of which sidethe data is recorded on the right side or the left side (if thedisc-like information recording carrier is employed, inner peripheralside or outer peripheral side) with respect to the inter-groove portion202.

For example, by comparing the (A+B) signal with the (C+D) signal, a sidein which the reproduction output deflects can be determined to be therecording side. This generates a strong effect if data recording isapplied to address recording. That is, because in the informationrecording carrier 1 of the present invention, the address data isrecorded alternately with the track 203 having the linear groove region,the address of only a track is outputted from every two tracks.

However, if which side the data is recorded on the right side or theleft side (inner peripheral side or outer peripheral side in thedisc-like information recording carrier) in the information recordingcarrier 1 of the present invention can be determined by the push-pullsignal, new binary information is obtained, so that address of a trackcan be obtained in one track.

FIG. 16 represents a method for reproducing such address informationfrom minute pattern 132 formed in the information recording carrier 1.

Referring to the same Figure, the minute pattern 132 is divided to tworegions macroscopically, which are clock region 401 for extractingclocks and address region 400 in which address data is recorded. Then,the latter is composed of high frequency portion and low frequencyportion.

The basic plane structure of FIG. 16 is the same as that of FIG. 12.

The reproduction light 91 traces a track from up to down as shown inFIG. 16. First, track 1 (Tr1, 232) is traced and then the track 2 (Tr2,232) is traced. Although at this time, a signal recorded in the groove231 having the wobbling region can be obtained using the (A+B)−(C+D)signal, the same signal is outputted from the track 1 (Tr, 232) and thetrack 2 (Tr2, 232). Therefore, the (A+B)−(C+D) signal does not indicatewhich an odd track is traced or an even track is traced.

However, if a determining means which determines that a side in whichreproduction output deflects in a constant cycle is a recording side bycomparing the (A+B) signal with the (C+D) signal is used here, which itis an odd track or an even track is determined so as to specify a track.

In case of FIG. 16, as a result of determination, a signal string ofright 0, 1, 0, 1, 1 is obtained when Tr1 is reproduced and then, asignal string of left 0, 1, 0, 1, 1 is obtained when Tr2 is reproduced.

Using such a reproduction method enables address and track to beautomatically and uniquely determined.

Meanwhile, such determination of odd/even tracks does not have to bealways carried out in the address region 400. Since it is continuousfrom the clock region 401, the determination may be carried out in theclock region 401 before or after the address region 400 is read.

Further, the determination may be carried out with track odd/evendetermination pit provided especially in addition to the address region400 and the clock region 401. Since the determining means at this timechanges depending on allocation of the pit and kind of the recordingcode, the method is not restricted to comparison between the (A+B)signal and the (C+D) signal.

Here, the supporting body 13, the recording layer 12 and the lighttransmission layer 11 in FIG. 15 will be described in detail.

The supporting body 13 is a base having the function for holding therecording layer 12 and the light transmission layer 11 formed thereonmechanically. Any one of synthetic resin, ceramic and metal is employedas its material. As the synthetic resin, preferably, various kinds ofthermoplastic resins and thermoset resin such as polycarbonate, polymethyl methacrylate, polystyrene, polycarbonate·polystyrene copolymer,polyvinyl chloride, alicyclic polyolefine, poly methyl pentene, andvarious kinds of energy beam setting resins (including examples ofultraviolet beam setting resin, visible light setting resin, electronbeam setting resin) are used. In the meantime, they may be syntheticresins in which metallic powder or ceramic powder is mixed.

As an example of ceramic, soda lime glass, soda alumino silicate glass,boro-silicated glass, crystal glass and the like are available. Further,as an example of metal, a metallic plate having light transmissioncharacteristic such as aluminum is also available.

For necessity of mechanical holding, preferably, the thickness of thesupporting body 13 is 0.3 to 3 mm, more preferably 0.5 to 2 mm. In casewhere the information recording carrier 1 is disc-like, preferably, thethickness of the supporting body 13 is designed so that the totalthickness of the supporting body 13, the recording layer 12, the lighttransmission layer 11 and the like is 1.2 mm for compatibility with aconventional optical disc.

The recording layer 12 is a thin film layer having the function forrecording or rewriting information. As material of this recording layer12, material which induces changes in reflectivity or refractivity orboth of them before or after the recording, represented by phase changematerial, material which induces change in rotation angle before orafter the recording represented by photo-magnetic material, and materialwhich induces change in refractivity or depth or both of them before orafter the recording represented by pigment material are employed.

Specific examples of the phase change material includes alloys ofindium, antimony, tellurium, selenium, germanium, bismuth, vanadium,gallium, platinum, gold, silver, copper, aluminum, silicone, palladium,tin, arsenic (alloys include oxide, nitride, carbide, sulfide,fluoride). Particularly, alloys such as GeSbTe base, AgInTeSb base,CuAlSbTe base, AgAlSbTe base are preferable. These alloys can contain atleast one element selected from groups consisting of Cu, Ba, Co, Cr, Ni,Pt, Si, Sr, Au, Cd, Li, Mo, Mn, Zn, Fe, Pb, Na, Cs, Ga, Pd, Bi, Sn, Ti,V, Ge, Se, S, As, Tl, In, Pd, Pt, Ni by 0.01 atom % or more to less than10 atoms % in total.

As for the composition of each element, for example, as GeSbTe system,Ge₂Sb₂Te₅, Ge₁Sb₂Te₄, Ge₈Sb₆₉Te₂₃, Ge₈Sb₇₄Te₁₈, Ge₅Sb₇₁Te₂₄,Ge₅Sb₇₆Te₁₉, Ge₁₀Sb₆₈Te₂₂, Ge₁₀Sb₇₂Te₁₈, and a system in which metalsuch as Sn, In is added to the GeSbTe system are available. As AgInSbTesystem, Ag₄In₄Sb₆₆Te₂₆, Ag₄In₄Sb₆₄Te₂₆, Ag₂In₆Sb₆₄Te₂₈, Ag₃In₅Sb₆₄Te₂₈,Ag₂In₆Sb₆₆Te₂₆, and a system in which metal or semiconductor such as Cu,Fe, Ge is added to the AgInSbTe system are available. Additionally,CuAlSbTe system and AgAlSbTe system are also available.

Specific examples of photo-magnetic material include alloys of terbium,cobalt, iron, gadolinium, chrome, neodymium, dysprosium, bismuth,palladium, samarium, holmium, proceodium, manganese, titanium,palladium, erbium, ytterbium, lutecium, tin and the like (alloys includeoxide, nitride, carbide, sulfide, fluoride). Particularly, this materialis preferred to be composed of alloy of transition metal and rare earthrepresented by TbFeCo, GdFeCo, DyFeCo and the like. Further, therecording layer 12 may be composed using alternately overlaid-layer filmof cobalt and platinum.

As specific example of pigment material, porphyrin pigment, iodocyaninpigment, phthalocyanine pigment, naphthlocyanine pigment, azo dyestuff,naphthoquinone pigment, fulgide pigment, polymethyne pigment, acridinepigments are available.

In the meantime, the recording layer 12 may incorporate or be loadedwith an auxiliary material in order to intensify its recordingperformance or reproduction performance as well as these materials whichcarry out recording.

For example, as the auxiliary material, it is permissible to use alloysof silicone, tantalum, zinc, magnesium, calcium, aluminum, chrome,zirconium and the like (alloys include oxide, nitride, carbide, sulfide,fluoride) and high reflective film (heat sink material of various alloyscontaining one or more of aluminum, gold, silver) such that it isoverlaid. Particularly, if the recording layer 12 is composed of phasechange material, the reflectivity can be adjusted to appropriate level(for example, reflectivity 12 to 24%) so as to increase the amount ofreproduction light and improve rewriting frequency, reproductioncharacteristic, recording characteristic, reproduction stability andstorage stability by overlaying dielectric material such as ZnS, SiO,SiN, SiC, AlO, AlN, MgF, ZrO on the aforementioned recording material.

The light transmission layer 11 has the function of introducingconverged reproduction light to the recording layer 12 with littleoptical distortion.

For example, preferably, material whose transmissibility is more than70%, more preferably more than 80% under reproduction wavelength of λ isused.

Since the light transmission layer 11 needs to have little opticalanisotropy, it is composed of material whose refractivity is less than±100 nm, more preferably less ±50 nm at 90° incident double path so asto suppress reduction of reproduction light.

As material having such characteristic, it is permissible to usesynthetic resin such as polycarbonate, poly methyl methacrylate,cellulose triacetate, cellulose diacetate, polystyrene,polycarbonate·polystyrene copolymer, polyvinyl chloride, alicyclicpolyolefine, poly methyl pentene.

The light transmission layer 11 may have the function for protectingmechanically and chemically. As material having such a function, it ispermissible to use material having high stiffness, such as transparentceramic (for example, soda lime glass, soda alumino silicate glass,boro-silicated glass, crystal glass), thermoset resin, energy linesetting resin (for example, ultraviolet beam setting resin, visiblelight setting resin, electron beam setting resin).

In order to reduce double refraction (optical anisotropy), preferablythe thickness of the light transmission layer 11 is than 2 mm, and morepreferably less than 1.2 mm.

If the information recording carrier 1 is loaded on an informationrecording carrier playback unit having NA of less than 0.7, preferablythe thickness of the light transmission layer 11 is less than 0.4 mm inorder to suppress optical aberration when the information recordingcarrier 1 is inclined, and particularly when NA is more than 0.85, it ispreferred to be less than 0.12 mm.

Further, the thickness thereof is preferred to be less than 0.02 mm soas to protect the recording layer 12 from being scratched. That is, ifNA is more than 0.85, its preferable range is 0.02 to 0.12 mm.

Further, deflection in the thickness in a plane is preferred to be±0.003 mm max, because the NA of the objective lens is large.Particularly when the NA of the objective lens is more than 0.85, it ispreferred to be less than ±0.002 mm. Further, if the NA of the objectivelens is 0.9, preferably, the thickness is less than ±0.001 mm.

In the meantime, the light transmission layer 11 is not restricted to asingle-layer structure shown in FIG. 15, but maybe of overlaid multiplelayers having the same function.

Although not shown, it is permissible to form a well known electrostaticpreventive layer, a lubrication layer, a hard coat layer or the like ona side opposite to the recording layer 12 of the light transmissionlayer 11.

As specific material of the lubrication layer, it is permissible to useliquid lubricant whose surface energy is adjusted by modifyinghydrocarbon polymer molecules with silicone or fluorine. In themeantime, the thickness of the lubrication layer is preferred to beabout 0.1 nm to 10 nm.

As specific material for the hard coat layer, it is permissible to usethermoset resin, various kinds of energy beam setting resin (includingexamples of ultraviolet beam setting resin, visible light setting resin,electron beam setting resin), humidity setting resin, multiple-liquidmixture setting resin, solvent contained thermoplastic resin, whichallows 70% or more light having the wavelength λ to be passed through.

Considering wear resistance of the light transmission layer 1, the hardcoat layer is preferred to have the pencil scratch test value based onJIS standard K5400 which is above a specific value. The hardest materialfor the objective lens in the information recording carrier playbackunit is glass and if considering this, the pencil scratch test value onthe hard coat layer is preferred to be more than H.

If the test value is below this value, generation of dust and dirt dueto scratch of the hard coat layer becomes conspicuous so that the errorrate drops rapidly.

Further, the thickness of the hard coat layer is preferred to be 0.001mm or more considering impact resistance and further less than 0.01 mmconsidering warp of the entire information recording carrier 1.

As another material for the hard coat layer, it is permissible to use asingle unit such as carbon, molybdenum, silicone or alloy (includingoxide, nitride, sulfide, fluoride, carbide), which allows 70% or morelight having the wavelength λ to pass through and has the pencil scratchtest value of above H (film thickness 1 to 1000 nm).

Further, although not shown, it is permissible to print a label on aside opposite to the recording layer 12 of the supporting body 13. Asprinting material, it is permissible to use various kinds of energy beamsetting resins (including ultraviolet beam setting resin, visible beamsetting resin, electron beam setting resin) containing various kinds ofpigments or dyes. The thickness is preferred to be 0.001 mm or moreconsidering visibility and further, less than 0.05 mm considering warpof the entire information recording carrier 1, 2, 3, 4.

Further, hologram or visible minute pattern for recognizing theinformation recording carrier 1 may be formed in other region than aspecific region used for recording.

Further, to improve mounting performance to a reproducing apparatus or arecording apparatus or protecting performance for handling, the entireinformation recording carrier 1 to 4 may be incorporated in a cartridge.

If the information recording carrier 1 to 4 is disc like, its size isnot limited, but may be selected from various sizes of 20 to 400 mm, forexample, it may be 30, 32, 35, 41, 51, 60, 65, 80, 88, 120, 130, 200,300, 356 mm.

In the meantime, as another application of the information recordingcarrier 1 of the present invention, it is permissible to employ sawtooth wave as its basic wave. That is, although not shown, the saw toothwave can take two values by mild riseup/steep fall and steep riseup/mildfall. Because interference with the data recording method of the presentinvention is small, multi-value data can be recorded by combination. Forexample, if the frequency shift modulation is binary, four value datacan be recorded by combination.

Further, a multi-layer stack like information recording carrier can beformed by expanding the information recording carrier 1 of the presentinvention. Particularly, as shown in FIG. 17, a two-layer informationrecording carrier 1 may be so constructed that address recording on thefirst layer is executed by frequency shift modulation with saw toothwave type 1 as its basic wave while the address recording on the secondlayer is executed by frequency shift modulation with saw tooth wave type2 as the basic wave.

Here, the saw tooth wave type 1 refers to for example, mild rise/steepfall and the saw tooth wave type 2 refers to for example, steeprise/mild fall. Such a structure enables rise vector and fall vector tobe generated clearly by inputting reproduced push-pull signal into ahigh band filter and extracting its differential components, therebyenabling the layer to be determined.

That is, determining whether the first layer or the second layer can becarried out more quickly than decoding of address. Thus, this isadvantageous for shortening access time for recording or reproduction.

FIG. 17 is a sectional view showing two-layered carrier gained bymodifying the thin type light transmission layer information recordingcarrier described in FIG. 13.

The information recording carrier 1 comprises the supporting body 13,the first recording layer 17, the first light transmission layer 16, thesecond recording layer 15 and the second light transmission layer 14,these layers being overlaid in the order. Common description to FIG. 13is omitted.

The function and composition material of the first recording layer 17and the second recording layer 15, and the function and compositionmaterial of the first light transmission layer 16 and the second lighttransmission layer 14 are basically the same as the function andcomposition material of the recording layer 12 and the lighttransmission layer 11 described in FIG. 13. A different point is thatoptimized material is used for each of those components for the laser 91to pass through the second recording layer 15 and be recorded in thefirst recording layer 17.

Next, a specific example of the present invention will be described.

EXAMPLE 1

A disc-like information recording carrier having the structure shown inFIG. 12 was manufactured.

The pitch P between the track 231 having the wobbling groove region andthe track 233 having the linear groove region is 0.32 μm, the width ofeach groove is 0.16 μm and the width of the inter-groove portion 233 is0.16 μm.

The track 231 having the wobbling groove region and the track 233 havingthe linear groove region are disposed in the land portion L in FIG. 13,while the inter-groove portion 232 is disposed in the groove portion G.

The track 231 having the wobbling groove region is comprised of addressregion 400 (5.5 μm long) and clock region 401 and six address regionsare disposed each turn.

The address region 400 and the clock region 401 employ sine wave astheir basic waves. The track 233 having the linear groove region employs360° continuous linear groove.

In the address region 400, as shown in FIG. 9, by frequency shiftmodulation in which a difference in phase between the high frequencyportion 305 and the low frequency portion 304 is ±π/7.6 and phasecontinuity at channel bit switching point is at random, address data wasrecorded in the information unit in which a wave in low frequencyportion served as a channel bit.

In the meanwhile, the frequency of the low frequency portion is matchedwith the single frequency of the clock region 401. Further, the highfrequency portion 305, the low frequency portion 304 and the clockregion 401 have the same amplitude.

As pre-treatment for recording, address data was subjected to base bandmodulation with Manchester code and further differential modulation.

As the disc-like information recording carrier 1, a phase rewritabledisc having the recording layer 12 made of mainly AgInSbTe was employedand this information recording carrier 1 which can executerecording/reproduction through the 0.1 mm light transmission layer 11was completed.

The laser beam 91 was projected to the groove portion G in the disc-likeinformation recording carrier 1 through the pickup 90 having thewavelength λ405 nm (gallium nitride light emission device) and NA 0.85so as to record/reproduce user data.

First, before recording, a single frequency was read from the clockregion according to the push-pull method so as to measure C/N.Consequently, an excellent clock signal of 35 dB in C/N was reproducedwithout any interference of adjacent address (RBW1kHz). Subsequently, anaddress region was reproduced selectively according to the push-pullmethod so as to measure the error rate of address. An excellent errorrate of 4.5E-5 was found. Further, the inner periphery and outerperiphery of the address could be determined excellently.

Subsequently, user recording was executed into the inter-groove portion232 in the disc-like information recording carrier 1. More specifically,random data of 2T-8T was recorded such that it was overlaid 10 times byusing modulation signal (17PP modulation) described in Japanese PatentApplication Laid-Open No. H11-346154 (1999).

The shortest mark length (2T) was set to 0.151 μm. When this recordingsignal was reproduced, an excellent error rate of jitter of 8.7% andrate 4E-6 was obtained. The error rate of address was 7E-5 when measuredagain and this was excellent error rate although a slight increase inerror was recognized. No interference between address information anduser data was recognized. Determination of the inner periphery and outerperiphery of address could be carried out excellently without beingdisturbed.

EXAMPLE 2

A disc like information recording carrier 1 having the structure shownin FIG. 12 was manufactured.

The pitch P between the track 231 having the wobbling groove region andthe track 233 having the liner groove region is 0.32 μm, the width ofeach groove is 0.16 μm and the width of the inter-groove portion 232 is0.16 μm.

The track 231 having the wobbling groove region and the track 233 havingthe linear groove region are disposed in the land L in FIG. 13 and theinter-groove portion 232 is disposed in the groove G.

The track 231 having the wobbling groove region is comprised of addressregion 400 (5.5 μm long) and clock region 401 and six address regionsare disposed each turn.

The address region 400 and the clock region 401 employ sine wave astheir basic waves. The track 233 having the linear groove region employs360° continuous linear groove.

In the address region 400, by frequency shift modulation in which adifference in phase between the high frequency portion 305 and the lowfrequency portion 304 is ±π/2.5 and phase continuity at channel bitswitching point is maintained, address data was recorded in theinformation unit in which a wave in low frequency portion served as achannel bit.

In the meanwhile, the frequency of the low frequency portion is matchedwith the single frequency of the clock region 401. Further, the highfrequency portion 305, the low frequency portion 304 and the clockregion 401 have the same amplitude.

As pre-treatment for recording, address data was subjected to base bandmodulation with Manchester code and further differential modulation.

As the disc-like information recording carrier 1, a phase rewritabledisc having the recording layer 12 made of mainly AgInSbTe was employedand this information recording carrier 1 which could executerecording/reproduction through the 0.1 mm light transmission layer 11was completed.

The laser beam 91 was projected to the groove portion G in the disc-likeinformation recording carrier 1 through the pickup 90 having thewavelength λ 405 nm (gallium nitride light emission device) and NA 0.85so as to record/reproduce user data.

First, before recording, a single frequency was read from the clockregion 401 according to the push-pull method so as to measure C/N.Consequently, an excellent clock signal of 35 dB in C/N was reproducedwithout any interference of adjacent address (RBW1kHz). Subsequently, anaddress region was reproduced selectively according to the push-pullmethod so as to measure the error rate of address. An excellent errorrate of 2.5E-5 was found. Further, the inner periphery and outerperiphery of the address could be determined excellently.

Subsequently, user recording was executed into the inter-groove portion232 in the disc-like information recording carrier 1. More specifically,random user data of 2T-10T and 13T (synchronous signal) was recordedsuch that it was overlaid 10 times by using modulation signal (D4, 6modulation) described in Japanese Patent Application No. 2001-080205.

The shortest mark length (2T) was set to 0.154 μm. When this recordingsignal was reproduced, an excellent error rate of jitter of 8.6% andrate 3.5E-6 was obtained. The error rate of address was 3E-5 whenmeasured again and this was excellent error rate although a slightincrease in error was recognized. No interference between addressinformation and user data was recognized. Determination of the innerperiphery and outer periphery of address could be carried outexcellently without being disturbed.

EXAMPLE 3

A disc-like information recording carrier having the structure shown inFIG. 12 was manufactured.

The pitch P between the track 231 having the wobbling groove region andthe track 233 having the linear groove region is 0.32 μm, the width ofeach groove is 0.16 μm and the width of the inter-groove portion 233 is0.16 μm.

The track 231 having the wobbling groove region and the track 233 havingthe linear groove region are disposed in the land portion L in FIG. 13while the inter-groove portion 232 is disposed in the groove portion G.

The track 231 having the wobbling groove region is comprised of addressregion 400 (30 μm long) and clock region 401 and three address regionsare disposed each turn.

The address region 400 and the clock region 401 employ sine wave astheir basic waves.

The track 233 having the linear groove region employs 360° continuouslinear groove.

In the address region 400, by frequency shift modulation in which adifference in phase between the high frequency portion and the lowfrequency portion is ±π/11 and phase continuity at channel bit switchingpoint is at random, address data was recorded in the information unit inwhich ten waves in low frequency portion served as a channel bit.

In the meanwhile, the frequency of the low frequency portion is matchedwith the single frequency of the clock region 401. Further, the highfrequency portion 305, the low frequency portion 304 and the clockregion 401 have the same amplitude.

As pre-treatment for recording, address data was subjected to base bandmodulation with Manchester code and further differential modulation.

As the disc-like information recording carrier 1, a phase rewritabledisc having the recording layer 12 made of mainly Ge doping SbTe wasemployed and this information recording carrier 1 which could executerecording/reproduction through the 0.1 mm light transmission layer 11was completed.

The laser beam 91 was projected to the groove portion G in the disc-likeinformation recording carrier 1 through the pickup 90 having thewavelength λ405 nm (gallium nitride light emission device) and NA 0.85so as to record/reproduce user data.

First, before recording, a single frequency was read from the clockregion according to the push-pull method so as to measure C/N.Consequently, an excellent clock signal of 35 dB in C/N was reproducedwithout any interference of adjacent address (RBW1kHz). Subsequently, anaddress region was reproduced selectively according to the push-pullmethod so as to measure the error rate of address. An excellent errorrate of 1E-4 was found. Further, the inner periphery and outer peripheryof the address could be determined excellently.

Subsequently, user recording was executed into the inter-groove portion232 in the disc-like information recording carrier 1. More specifically,random data of 3T-11 and 12T (synchronous signal) was recorded such thatit was overlaid 100 times by using modulation signal (D8-15 modulation)described in Japanese Patent Application Laid-Open No. 2000-286709.

The shortest mark length (3T) was set to 0.185 μm. When this recordingsignal was reproduced, an excellent error rate of jitter of 7.7% andrate 8E-7 was obtained. The error rate of address was 2.5E-4 whenmeasured again and this was excellent error rate although a slightincrease in error was recognized. No interference between addressinformation and user data was recognized. Determination of the innerperiphery and outer periphery of address could be carried outexcellently without being disturbed.

<Points of the Present Invention>

The examples of the present invention have been described above withreference to the examples 1 to 3. The main feature of the presentinvention is that the information recording carrier having at least thegroove wobbling region is employed and that data is recorded wobblinglyinto this wobbling region by frequency shift modulation. Consequently,even if a mark is recorded in the recording layer so that mixing occurs,the address can be reproduced at a low error rate.

The second main feature of the present invention is the informationrecording carrier in which the wobbling groove and the linear groove aredisposed alternately. This can reduce reproduction cross-talk withadjacent track very remarkably. The examples above 1 to 3 are examplescontaining these two features however, the present invention is notrestricted to these examples.

As evident from the above description, in the information recordingcarrier of the present invention, plural grooves formed in theinformation recording carrier have at least wobbling regions and data isrecorded wobblingly in this wobbling region by frequency shiftmodulation. As a result, digital data such as address information can beread out excellently by separating reproduced data depending ondifference in frequency. Particularly, if the phase relation between thehigh frequency portion and the low frequency portion is set to ±(π/20.5)to ±(π/0.75), the digital data can be read at a low error rate.

Particularly if the track having the wobbling groove region modulated byfrequency shift modulation and the track having the linear groove regionare disposed alternately, digital data such as address information canbe read out excellently without cross-talk from data reproduced from thetrack having the wobbling groove region and the track having the lineargroove region.

Further, if any mark such as user data is recorded in the inter-grooveportion between the track having the wobbling groove region and thetrack having the linear groove region, mutual interference between thetrack having the wobbling groove region and the track having the lineargroove region, which are located adjacent this inter-groove portion,hardly occurs. Thus, an information recording carrier capable of holdinga high density recording capacity can be provided without falling userrecording capacity to be recorded in each track in the inter-grooveportion.

It should be understood that many modifications and adaptations of theinvention will become apparent to those skilled in the art and it isintended to encompass such obvious modifications and changes in thescope of the claims appended hereto.

1. An information recording carrier having minute pattern includingplural grooves or lands formed to be substantially in parallel andadjacent to each other, comprising: a supporting body having the minutepattern; a recording layer formed on the minute pattern formed on thesupporting body; and a light transmission layer formed on the recordinglayer, wherein when a pitch of each groove or land is P, a wavelength ofa laser beam is λ, and a numerical aperture of an objective lens is NA,the minute pattern is formed under a relation of P<λ/NA; wherein theplural grooves or lands include at least a wobbling region and data isrecorded wobblingly in the wobbling region by frequency shiftmodulation; wherein a phase of a high frequency portion and a phase of alow frequency portion are continuous at a border between the highfrequency portion and the low frequency portion composing the frequencyshift modulation; and wherein a frequency ratio between a firstfrequency of the high frequency portion and a second frequency of thelow frequency portion is 1.5.
 2. A method of reproducing the informationrecording carrier as recited in claim 1, comprising: irradiating thelaser light on the recording layer through the light transmission layerin such a way that the laser light tracks the grooves or lands therebeneath; detecting the laser light reflected by the recording layer; andrecognizing the frequencies that are used in frequency shift modulationthrough the detected laser light.
 3. The reproducing method recited inclaim 2, wherein the wavelength of a laser beam λ, is 405 nm, andwherein the numerical aperture of an objective lens NA is 0.85.